BACKGROUND: Antioxidants have potential to protect normal tissues against radiation-induced damage, but must not also protect tumor cells during radiotherapy. The major objectives were to determine whether a metalloporphyrin antioxidant affects prostate tumor response to radiation and identify possible mechanisms of interaction. MATERIALS AND METHODS: C57BL/6 mice with RM-9 tumor were treated with manganese (III) meso-tetrakis(1,3-diethylimidazolium-2-yl)porphyrin (MnTDE-2-ImP) and 10 gray (Gy) radiation. Tumor volume was quantified and a subset/group was evaluated for hypoxia-inducible factor-1? (HIF-1?), bone marrow-derived cell populations, and cytokines. RESULTS: The addition of MnTDE-2-ImP transiently increased tumor response compared to radiation alone. The group receiving drug plus radiation had reduced intratumoral HIF-1? and decreased capacity to secrete TNF-?, whereas production of IL-4 was increased. There were no toxicities associated with combination treatment. CONCLUSION: The results demonstrate that MnTDE-2-ImP did not protect the RM-9 prostate tumor against radiation; instead, radiation effectiveness was modestly increased. Possible mechanisms include reduction of radiation-induced HIF-1? and an altered cytokine profile.

Introduction: Lipopolysaccharide (LPS) is a major cause of septic shock and death due to infection with Gram-negative bacteria. The purpose of this study was to quantify the effects of whole-body irradiation on lymphocyte populations during response to challenge with LPS. Materials and methods: C57BL/6 mice (n = 10/group) were irradiated whole-body with 3 gray (Gy) ?-rays in a single fraction at 0.8 Gy/min. LPS (E. coli serotype 0111:B4) at 1 mg/kg was injected intraperitoneally 10 days later and mice were euthanized at 60 min and days 1, 7, and 14 post-inoculation for analyses. Results: Significant interactions between radiation and LPS were noted in circulating and splenic lymphocyte subpopulations, including T, B, and NK-cells, particularly at the early time points. There were significant interactions on circulating, but not splenic, CD62L+ T-cell populations. However, there were no interactions on CD62L+ B-cells. Finally, there were significant interactions in both early and late blastogenic responses. Conclusion: The data support the conclusion that response to infection with Gram-negative bacteria may be significantly compromised by exposure to ionizing radiation.

This study assessed the feasibility of an ex vivo Sca-1+ cell-based systemic FGF-2 gene therapy to promote endosteal bone formation. Sca-1 cells were used because of their ability to home and engraft into the bone marrow cavity. The human FGF gene was modified to increase protein secretion and stability by adding the BMP-2/4 hybrid signal sequence and by mutating two key cysteines. Retro-orbital injection of SCA-1+ cells transduced with an MLV-based vector expressing the modified FGF=2 gene into sub-lethally irradiated W41/W41 recipient mice resulted in long-term engraftment, marked elevation in serum FGF-2 level (>100-fold of normal value). Increase in serum bone formation markers, and massive endosteal bone formation. In recipient mice showing very high serum FGF-2 levels (>4,000 pg/ml), this enhanced endosteal bone formation was so robust that the marrow space was completely filled up with bony tissue and there was insufficient calcium available for the mineralization of all the newly formed bone, which led to hypocalcemia, secondary hyperparathyroidism, and osteomalacia. These side effects appeared to be dose-related. In conclusion, this study provided compelling test-of-principle evidence for the feasibility of a Sca-1+ cell-based ex vivo systemic FGF-2 gene therapy strategy to promote endosteal bone formation.

The dose of radiation that can be safely delivered to cancers residing in sensitive areas such as the lungs is limited by concern for normal tissue damage. Therapies that target tumor vasculature have potential to enhance the efficacy of radiotherapy, with minimal risk for toxicity. We constructed a unique plasmid, pXLG-mEndo, containing the mouse endostatin gene. A significantly greater anti-tumor effect was obtained against Lewis lung carcinoma (LLC) in mice when pXLG-mEndo was combined with radiation compared to radiation alone. Here we report results of cellular and cytokine assessments performed 1 day after treatment. These analyses were done to obtain baseline data on leukocytes that affect angiogenesis, as well as anti-tumor immunity, and to detect possible treatment-related toxicities. White blood cell counts were dramatically elevated in blood and spleens of untreated tumor-bearing mice, primarily due to granulocytosis. Overall, the effect of radiation was more evident than that of the plasmids (pXLG-mEndo and parental pWS4); radiosensitivity of specific lymphocyte subsets was variable (B > T > NK; CD8+ Tc > CD4+ Th). Tumor presence resulted in dramatically elevated interleukin-2 (IL-2) and decreased tumor necrosis factor-? (TNF-?) in supernatants of activated splenocytes, but had no significant effect on interferon-? (IFN-?). Administration of pXLG-mEndo, radiation, or both modified the tumor-induced aberrations in IL-2 and TNF-?; IFN-? production was decreased by radiation. Red blood cell counts, hemoglobin, and hematocrit were low in tumor-bearing mice, but there were no treatment-related differences among groups. Platelet counts were reduced, whereas their volumes were increased in tumor-bearing mice; both parameters were only slightly affected by either pXLG-mEndo or control plasmid injection, however. The data demonstrate in the Lewis lung carcinoma model that tumor-localized endostatin gene therapy and radiation had significant effects on cells and cytokines that can influence angiogenesis, tumor growth and immune status.

Cancer patients receiving radiation therapy are exposed to photon (gamma/X-ray), electron, and less commonly proton radiation. Similarly, astronauts on exploratory missions will be exposed to extended periods of lower-dose radiation from multiple sources and of multiple types, including heavy ions. Therapeutic doses of radiation have been shown to have deleterious consequences on bone health, occasionally causing osteoradionecrosis and spontaneous fractures. However, no animal model exists to study the cause of radiation-induced osteoporosis. Additionally, the effect of lower doses of ionizing radiation, including heavy ions, on general bone quality has not been investigated. This study presents data developing a murine model for radiation-induced bone loss. Female C57BL/6 mice were exposed to gamma, proton, carbon, or iron radiation at 2-Gray doses, representing both a clinical treatment fraction and spaceflight exposure for an exploratory mission. Mice were euthanized 110 days after irradiation. The proximal tibiae and femur diaphyses were analyzed using microcomputed tomography. Results demonstrate profound changes in trabecular architecture. Significant losses in trabecular bone volume fraction were observed for all radiation species: gamma, (-29%), proton (-35%), carbon (-39%), and iron (-34%). Trabecular connectivity density, thickness, spacing, and number were also affected. These data have clear implications for clinical radiotherapy in that bone loss in an animal model has been demonstrated at low doses. Additionally, these data suggest that space radiation has the potential to exacerbate the bone loss caused by microgravity, although lower doses and dose rates need to be studied.

Cancer patients receiving radiation therapy are exposed to photon (gamma/X-ray), electron, and less commonly proton radiation. Similarly, astronauts on exploratory missions will be exposed to extended periods of lower-dose radiation from multiple sources and of multiple types, including heavy ions. Therapeutic doses of radiation have been shown to have deleterious consequences on bone health, occasionally causing osteoradionecrosis and spontaneous fractures. However, no animal model exists to study the cause of radiation-induced osteoporosis. Additionally, the effect of lower doses of ionizing radiation, including heavy ions, on general bone quality has not been investigated. This study presents data developing a murine model for radiation-induced bone loss. Female C57BL/6 mice were exposed to gamma, proton, carbon, or iron radiation at 2-Gray doses, representing both a clinical treatment fraction and spaceflight exposure for an exploratory mission. Mice were euthanized 110 days after irradiation. The proximal tibiae and femur diaphyses were analyzed using microcomputed tomography. Results demonstrate profound changes in trabecular architecture. Significant losses in trabecular bone volume fraction were observed for all radiation species: gamma, (-29%), proton (-35%), carbon (-39%), and iron (-34%). Trabecular connectivity density, thickness, spacing, and number were also affected. These data have clear implications for clinical radiotherapy in that bone loss in an animal model has been demonstrated at low doses. Additionally, these data suggest that space radiation has the potential to exacerbate the bone loss caused by microgravity, although lower doses and dose rates need to be studied.

The effects of high-linear energy transfer (LET) radiation on immune function have not yet been clearly established. The major goal of this portion of the study was to evaluate leukocyte responses after whole-body high-LET irradiation. C57BL/6 mice were exposed to 0, 0.5, 2, and 3 gray (Gy) 56^Fe^26+ (1055 MeV/nucleon, 148.2 keV/?m) and euthanized 4 days post-exposure. Spontaneous synthesis of DNA in blood and spleen cells was significantly increased in groups receiving either 2 or 3 Gy (P